Bss Based I/q Imbalance Compensation in Communication Receivers in the Presence of Symbol Timing Errors

In I/Q processing receivers, matching the amplitudes and phases of the Iand Q-branches is of major concern. In practise, matching can never be perfect in the analog front-end which results in insufficient rejection of the image frequency band. As a consequence, the desired channel signal is interfered by up to 50-100 dB stronger image signal and some kind of imbalance compensation is needed. In this paper, the interference due to imbalancing is modelled by instantaneous linear mixing model and the compensation is carried out by a blind source separation (BSS) method. The effects of symbol timing errors on EASI algorithm based compensation structure are analyzed both analytically and through computer simulations. The obtained results indicate that timing errors degrade the performance of the proposed method. The effects of timing errors can, however, be reduced with proper selection of non-linearity in the EASI algorithm.